Radio frequency (RF) is used extensively in various short-distance wireless communications. Referring to FIG. 1, in a surface computer 10, an RF device 11 such as a cell phone with a radio frequency identification (RFID) tag placed on a display panel 12 communicates with a computer host 14 through an RF module 13, which includes an antenna and an associated RF circuit and is located at the back side of the display panel 12. Note that in this application, the computer host 14 may be more versatile given that the position of the RF device 11 on the display panel 12 is known. For example, via processing and transmission using the computer host 14, pictures saved in the RF device 11 may be displayed around the location of the RF device 11, e.g., on the display panel 12 for the user to view. For another example, when there are two or more RF devices on the display panel 12, the computer host 14 needs to locate the RF devices in order to identify the position of each RF device to proceed with subsequent communications.